Opponents accused Mursi, who has issued a decree that putshis decisions above legal challenge until a new parliament iselected, of being the new Mubarak and hijacking the revolution.

"The people want to bring down the regime," shoutedprotesters in Tahrir, echoing a chant used in the uprising thatforced Mubarak to step down. "Get out, Mursi," they chanted,along with "Mubarak tell Mursi, jail comes after the throne."

The United States, the European Union and the United Nationsexpressed concern at Mursi's move.

Mursi's aides said the presidential decree was intended tospeed up a protracted transition that has been hindered by legalobstacles but Mursi's rivals condemned him as an autocraticpharaoh who wanted to impose his Islamist vision on Egypt.

"I am for all Egyptians. I will not be biased against anyson of Egypt," Mursi said on a stage outside the presidentialpalace, adding that he was working for social and economicstability and the rotation of power.

"Opposition in Egypt does not worry me, but it has to bereal and strong," he said, seeking to placate his critics andtelling Egyptians that he was committed to the revolution. "Goforward, always forward ... to a new Egypt."

Buoyed by accolades from around the world for mediating atruce between Hamas and Israel in the Gaza Strip, Mursi onThursday ordered that an Islamist-dominated assembly writing thenew constitution could not be dissolved by legal challenges.

"Mursi a 'temporary' dictator," was the headline in theindependent daily Al-Masry Al-Youm.

Mursi, an Islamist whose roots are in the MuslimBrotherhood, also gave himself wide powers that allowed him tosack the unpopular general prosecutor and opened the door for aretrial for Mubarak and his aides.

The president's decree aimed to end the logjam and pushEgypt, the Arab world's most populous nation, more quickly along its democratic path, the presidential spokesman said.

"President Mursi said we must go out of the bottleneckwithout breaking the bottle," Yasser Ali told Reuters.

TURBULENCE AND TURMOIL

The president's decree said any decrees he issued while noparliament sat could not be challenged, moves that consolidatedhis power but look set to polarise Egypt further, threateningmore turbulence in a nation at the heart of the Arab Spring.

The turmoil has weighed heavily on Egypt's faltering economythat was thrown a lifeline this week when a preliminary deal wasreached with the International Monetary Fund for a $4.8 billionloan. But it also means unpopular economic measures.

In Alexandria, north of Cairo, protesters ransacked anoffice of the Brotherhood's political party, burning books andchairs in the street. Supporters of Mursi and opponents clashedelsewhere in the city, leaving 12 injured.

A party building was also attacked by stone-throwingprotesters in Port Said, and demonstrators in Suez threw petrolbombs that burned banners outside the party building.

Although Washington praised Egypt for its part in bringingIsraelis and Palestinians to a ceasefire on Wednesday, itexpressed concern about Mursi's move.

"The decisions and declarations announced on November 22raise concerns for many Egyptians and for the internationalcommunity," State Department spokeswoman Victoria Nuland said ina statement.

The United States has been concerned about the fate of whatwas once a close ally under Mubarak, who preserved Egypt's 1979peace treaty with Israel.

The European Union urged Mursi to respect the democraticprocess, while the United Nations expressed fears about humanrights.

"We are very concerned about the possible huge ramificationsof this declaration on human rights and the rule of law inEgypt," Rupert Colville, spokesman for the U.N. Human RightsCommissioner Navi Pillay, said at the United Nations in Geneva.

"ANOTHER DICTATOR"

"The decree is basically a coup on state institutions andthe rule of law that is likely to undermine the revolution andthe transition to democracy," said Mervat Ahmed, an independentactivist in Tahrir protesting against the decree. "I worry Mursiwill be another dictator like the one before him."